.\"	$OpenBSD: genassym.cf.5,v 1.10 2014/07/05 07:18:33 jsg Exp $
.\"	$NetBSD: genassym.cf.5,v 1.8 2001/06/19 12:34:27 wiz Exp $
.\"
.\" Copyright (c) 1997 Matthias Pfaller.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
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.Dd $Mdocdate: July 5 2014 $
.Dt GENASSYM.CF 5
.Os
.Sh NAME
.Nm genassym.cf
.Nd assym.h definition file
.Sh DESCRIPTION
The
.Nm
file is used by
.Xr genassym.sh 8
to make constant C expressions known to assembler source files.
.Pp
Lines starting with '#' are discarded by
.Xr genassym.sh 8 .
Lines starting with
.Em include ,
.Em ifdef ,
.Em if ,
.Em else
or
.Em endif
are preceded with '#' and passed otherwise unmodified to the C compiler.
.Pp
Lines starting with
.Em quote
get passed on with the
.Em quote
command removed.
.Pp
The first word after a
.Em define
command is taken as a CPP identifier and the rest of the line has to be
a constant C expression.
The output of
.Xr genassym.sh 8
will assign the numerical value of this expression to the CPP identifier.
.Pp
.Em "export foo"
.br
is a shorthand for
.br
.Em "define foo foo" .
.Pp
.Em "struct foo"
.br
remembers foo for the
.Em member
command and does a
.br
.Em "define FOO_SIZEOF sizeof(foo)" ,
.br
with the structure name converted to upper
case.
.Pp
.Em "member foo"
.br
does a
.br
.Em "define FOO offsetof(<last struct>, foo)" .
.br
The two argument form of
.Em "member" ,
as
.br
.Em "member foo bar"
.br
does a
.br
.Em "define FOO offsetof(<last struct>, bar)" ,
.br
with its first argument converted to upper case.
In the case where struct was
invoked with an extra argument, as in
.br
.Em "struct foo PREFIX_" ,
.br
the first argument of member will be prefixed by the remembered prefix, before
being converted to upper case.
.Pp
.Em "union foo"
.br
is similar to the
.Em struct
command, but applies to a union instead of a struct.
.Pp
.Em "config <ctype> <gcc constraint> <asm print modifier>"
.br
can be used to customize the output of
.Xr genassym.sh 8 .
.br
When producing C output, values are cast to <ctype> (default: long)
before they get handed to printf.
<gcc constraint> (default: n) is the constraint used in the __asm__ statements.
<asm print modifier> (default: empty) can be used to force gcc to output
operands in different ways than normal.
The "a" modifier e.g. stops gcc from emitting immediate
prefixes in front of constants for the i386 port.
.Sh FILES
.Pa /sys/arch/${MACHINE}/${MACHINE}/genassym.cf
.Sh SEE ALSO
.Xr genassym.sh 8
.Sh HISTORY
The first use of
.Nm
files occurred in
.Ox 2.2 .
Its use was generalized to all ports for
.Ox 3.0 .
The
.Em union
command appeared in
.Ox 3.5 .
